Comparison
of ASL Measures of Cerebrovascular Reactivity to CO2 Using
Different Respiratory Manipulations

ASL measurements of the cerebrovascular reactivity to
CO2 (CVR) provide an index of the cerebral vasculatures health
status and are also an important input for calibrated MRI. CVR is expressed
as the increase in ASL-flow signal that is induced per unit increase in
respiratory levels of CO2. We examined whether different
respiratory manipulations lead to consistent measures of CVR. We found that
because of the non-linearity of CO2-CBF dose-response curve, CVR
values differ according to the manipulated levels of CO2. However,
estimates tend to converge when CVR is expressed as the percent increase in
flow signal.